The nucleus of the cell is a membrane-bound organelle that includes the nuclear envelope, nucleoli, and nuclear lamina and is the site of gene expression. Nuclear structure can be selectively visualized by staining nuclear proteins or directly staining nucleic acids. Cell-permeant nucleic acid stains make it possible to stain live cells or tissues with minimal processing to reveal the natural location of cells in tissues and provide a means to follow nuclear changes throughout cellular processes, from mitosis to apoptosis.

ReadyProbes® nuclear dyes

ReadyProbes® reagents provide the easiest fluorescent staining method for nucleic acids. Formulated for room-temperature storage, they are provided in convenient dropper bottles for ease of use. Just add two drops per milliliter of solution to stain your cells. We offer a selection of ReadyProbes® nucleic acid stains with a choice of wavelengths for multiplexing and colocalization in either live or fixed cells

CellLight® reagents for nuclear proteins

A choice of CellLight® reagents for labeling the nucleus allows you to label histone proteins using a histone 2B sequence (13.7 kDa) to follow the dynamics of chromosomal behavior, or localize fluorescent protein to the nucleus using an SV40 nuclear localization sequence (1.0 kDa). CellLight® proteins can be multiplexed with other fluorescent probes for analysis in live cells, or after fixation for colocalization studies. These ready-to-use constructs express fluorescent fusion proteins after a simple transfection step, and they work like cell stains with minimal toxicity or chemical disruption.

High-performance nuclear dyes

Ideal nuclear dyes should exhibit affinity for both DNA and RNA and display enhanced fluorescence upon binding. For live-cell staining they should be permeant to eukaryotic and prokaryotic membranes and result in minimal toxicity to the cell. For fixed-cell staining, they should be stable and selective. Some of the highest-affinity DNA stains used with fixed cells are also used as dead-cell stains because they are impermeant to eukaryotic or prokaryotic cell membranes

We offer a selection of Molecular Probes® nucleic acid stains with a choice of wavelengths for multiplexing and colocalization in either live or fixed cells.

Staining the nucleolus

Nucleoli are non–membrane-bound bodies found within the nucleus and are the site where ribosomal RNA is transcribed. The SYTO® RNASelect™ Green Fluorescent Cell Stain is a cell-permeant nucleic acid stain that is selective for RNA. Although virtually nonfluorescent in the absence of nucleic acids, the SYTO® RNASelect™ stain exhibits bright green fluorescence when bound to RNA, but only a weak fluorescent signal when bound to DNA. The SYTO® RNASelect™ stain can be used to detect the nucleoli, and cells may be counterstained with a nuclear stain such as DAPI.

High-content screening (HCS)

Versatile HCS NuclearMask™ stains can be used to measure DNA content and perform cell demarcation with live or formaldehyde-fixed cells on high-content imaging and analysis (HCS) platforms. HCS NuclearMask™ stains are available in a choice of colors for multiplexing flexibility with other functional and structural probes to ask complex biological questions.